1. Field of the Invention
The present invention relates to the generation of a digital representation of an image, such as by scanning an image with light. More particularly, one embodiment of the present invention provides a method and system which may be used to correct image defects.
2. Description of Related Art
Photographs, slides, documents and other images are often electronically scanned to produce an electronic or digital representation of the image. The digital representation of the image is often captured, for example, by scanning the image with light in order to generate a digital representation of the image. The digital representation of the image may be stored (e.g., as a data file stored on an optical or magnetic disc), manipulated, displayed (such as on a video monitor or other suitable display device), and/or used to prepare a reproduction of the image on a medium (e.g., printed on a suitable substrate such as paper).
Since image capture techniques such as scanning essentially produce a digital xe2x80x9ccopyxe2x80x9d of the original image, the digital copy will necessarily include any defects present in the image substrate. For example, surface defects such as dust, scratches, fingerprints, smudges, and the like which are present on the original image substrate will also be present in the digital representation of that image generated by scanning.
Recently, methods for eliminating defects in electronically captured images have been developed. For example, one conventional method utilizes both visible and infrared light for scanning. The addition of an infrared scan allows surface defects to be eliminated from the digital representation of the image. While scanning an image with both visible and infrared light is an effective technique for eliminating image defects, this method can be difficult to implement.
The present invention provides a method for generating a digital representation of an image, comprising: applying visible and infrared light to an image storing medium which includes the image; directing the visible and infrared light which is reflected from or transmitted through the image storing medium to a reflective surface, wherein the visible light is reflected by the reflective surface towards a first sensor and the infrared light is transmitted through the reflective surface towards a second sensor; detecting the visible light which is reflected from or transmitted through the image storing medium at the first sensor in order to provide a first image signal; and detecting the infrared light which is reflected from or transmitted through the image storing medium at the second sensor in order to provide a second image signal. The second image signal may be used to modify the first image signal to generate a modified digital representation of the image. Alternatively, the visible light may be transmitted through the reflective surface towards the first sensor, and the infrared light reflected by the reflective surface towards the second sensor.
The visible and infrared light may be applied simultaneously to the image storing medium from the same light source, or separate infrared and visible light sources may be utilized. The system may be configured such that the visible light may be focused on the first sensor, and the infrared light may be focused on the second sensor. For example, the optical distance between the image storing medium and the first sensor may be different from the optical distance between the image storing medium and the second sensor, thus allowing the visible and infrared light to be individually focused on their respective sensors. In one embodiment, the reflective surface comprises a cold mirror, while in another embodiment the reflective surface comprises a hot mirror.
The first sensor may comprise a trilinear CCD array which is responsive to visible light, and the second sensor may comprise one or more linear CCD arrays which are responsive to infrared light (such as a conventional trilinear CCD array). The methods of the present invention may be employed with a variety of image storing media, particularly transparent media such as film (both positive and negative films). When a transparent media is employed, the detecting steps may comprise detecting light which is transmitted through the transparent medium.
A digital representation of an image generated by the above methods is also provided herein. The original image may include surface defects, while these surface defects are substantially absent in the digital representation of the image.
The present invention further provides a system for use in generating a digital representation of an image, and this system may comprise: one or more light sources operable to apply first and second types of light to an image storing medium having an image; a first sensor responsive to at least the first type of light; a second sensor responsive to at least the second type of light; and a reflective surface which reflects the first type of light and transmits the second type of light. The reflective surface may be positioned such that when the first and second types of light are applied to an image storing medium, the first type of light which is reflected from or transmitted through the image storing medium will be reflected towards the first sensor and the second type of light which is reflected from or transmitted through the image storing medium will be transmitted through the reflective surface towards the second sensor.
The system may also be configured such that the first type of light may be focused on the first sensor, and the second type of light may be focused on the second sensor. For example, the optical distance between the image storing medium and the first sensor and the optical distance between the image storing medium and the second sensor may be adjusted independently of one another. In one embodiment, the first and second sensors are movable with respect to the reflective surface such that the first and second types of light may be focused on their respective first and second sensors. The system may be configured, for example, as a scanner.
The first and second types of light are preferably of a different wavelength, with the wavelength of the second light chosen for acquiring data indicative of defects in the original image storing medium. In this manner, the second image signal provides a map of defects which may be used to modify the first image signal and generate a digital representation which does not include the defects. For example, the first light may comprise visible light, and the second light may comprise infrared light.